1. Field of the Invention
The present invention relates to a method for detecting a rotation direction of an ignition device during an operation of the ignition device, particularly a magneto ignition unit or device for an internal combustion engine.
2. Description of the Background Art
Such ignition devices are typically used in a hand-guided tool with a combustion engine as the internal combustion engine. To make sure that no ignition spark forms in a reverse operation of the combustion engine and thus to protect the internal combustion engine operated with such an ignition device from a reverse operation. It is known, for example, from DE 36 08 740 A1, which corresponds to U.S. Pat. No. 4,722,311, to provide a rotation direction detector for detecting the rotation direction, which is intended in the case of a wrong rotation direction of the engine to prevent the discharging of ignition pulses. For realization, electronics are proposed for determining the number of positive and negative half waves induced in a generator electromagnet (magnetic generator).
In the conventional structure of such an ignition device with a magnet wheel coupled to the combustion engine, for example, to its crankshaft, and with a typically U-shaped iron core with a coil (charging and/or ignition coil) arranged on at least one of its core legs, an induced voltage results in the coil depending on the rotation direction of the magnet wheel provided with permanent magnets, whereby the coil voltage has negative and positive half waves.
In the conventional ignition device, the electronics infer the rotation direction of the magnet wheel from the number of the positive and/or negative half waves. As in prior concepts of rotation direction detection or for other purposes, for example, for determining the angular positions and for possible signal processing, active components, particularly transistors, are employed in the conventional device as well.